Systems for Isolation of a Needle-based Infusion Set

ABSTRACT

A safety needle assembly of an infusion set for infusing fluids into a subcutaneously implanted access port is disclosed. The needle assembly is configured to prevent fluid/vapor escape therefrom so as to reduce or prevent fluid exposure to a clinician using the needle assembly. In one embodiment, the needle assembly comprises a handle portion including a needle extending therefrom, the needle defining a lumen for passage of a fluid therethrough. The needle assembly also includes a safety assembly defining a needle hole through which the needle initially extends. The safety assembly is selectively and axially slidable along the needle in order to shield a distal tip of the needle and prevent user contact therewith. A fluid isolation component is included in the safety assembly for isolating fluid escape from the needle to prevent exposure to a clinician.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No. 13/229,573, filed Sep. 9, 2011, now U.S. Patent No. 9,248,234, which claims the benefit of U.S. Provisional Patent Application No. 61/381,762, filed Sep. 10, 2010, each of which is incorporated herein by reference in its entirety.

BRIEF SUMMARY

Briefly summarized, embodiments of the present invention are directed to a safety needle assembly of an infusion set for infusing fluids into a subcutaneously implanted access port. The needle assembly is configured to prevent fluid escape therefrom so as to reduce or prevent fluid exposure to a clinician using the needle assembly.

In one embodiment, the needle assembly comprises a handle portion including a needle extending therefrom, the needle defining a lumen for passage of a fluid therethrough. The needle assembly also includes a safety assembly defining a needle hole through which the needle initially extends. The safety assembly is axially slidable along the needle in order to shield a distal tip of the needle and prevent user contact therewith. A fluid isolation component is included in the safety assembly for isolating fluid escape from the needle to prevent exposure to a clinician.

These and other features of embodiments of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of embodiments of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the present disclosure will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. Example embodiments of the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 is a perspective view of an infusion set including a safety needle assembly according to one embodiment;

FIG. 2 is a side view of the needle assembly of FIG. 1;

FIGS. 3A-3C show actuation of needle assembly of FIG. 1;

FIG. 4 shows a perspective view of an infusion set including a safety needle assembly in a first configuration according to one embodiment;

FIG. 5 shows a perspective view of the infusion set of FIG. 4 with the safety needle assembly in a second configuration;

FIGS. 6A-6C show actuation of the safety needle assembly of FIGS. 4 and 5

FIGS. 7A-7C shows actuation of a safety needle assembly according to another embodiment;

FIGS. 8A and 8B show a bottom view of a safety needle assembly including a fluid isolation component according to one embodiment;

FIGS. 9A and 9B are cross sectional side views of a safety needle assembly including a fluid isolation component according to one embodiment;

FIG. 10 is a cross sectional side view of a safety needle assembly including a fluid isolation component according to one embodiment;

FIG. 11 is a perspective view of a safety needle assembly according to one embodiment;

FIGS. 12A and 12B are bottom views of the safety needle assembly of FIG. 11;

FIG. 13 is a top view of a shutter of the safety needle assembly of FIG. 10, including a fluid isolation component according to one embodiment;

FIG. 14 is a perspective view of the shutter of FIG. 13 including the fluid isolation component;

FIG. 15 is a cross sectional side view of a safety needle assembly according to one embodiment;

FIGS. 16A and 16B are various views of a safety needle assembly according to one embodiment;

FIG. 17 is a cross sectional side view of a luer connector including a fluid isolation component according to one embodiment;

FIGS. 18A-18B are cross sectional side views of the luer connector of FIG. 17 during use;

FIGS. 19A and 19B show various views of a fluid isolation component together with an infusion set, according to one embodiment; and

FIG. 20 is a bottom view of a safety needle assembly including a fluid isolation component according to one embodiment.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made to figures wherein like structures will be provided with like reference designations. It is understood that the drawings are diagrammatic and schematic representations of exemplary embodiments of the present invention, and are neither limiting nor necessarily drawn to scale.

For clarity it is to be understood that the word “proximal” refers to a direction relatively closer to a clinician using the device to be described herein, while the word “distal” refers to a direction relatively further from the clinician. For example, the end of a needle placed within the body of a patient is considered a distal end of the needle, while the needle end remaining outside the body is a proximal end of the needle. Also, the words “including,” “has,” and “having,” as used herein, including the claims, shall have the same meaning as the word “comprising.”

Embodiments of the present invention are generally directed to a safety infusion set and accompanying needle assembly for infusing fluids, such as chemotherapy agents or other medicaments for example, into an access port or other medical device subcutaneously implanted into the body of a patient. The infusion set and/or needle assembly includes one or more components for isolation of the fluid, including vapors thereof, which may otherwise leak from a needle or other portion of the infusion set. This in turn reduces or prevents possible clinician exposure to the fluid/vapors, which in some cases may be hazardous. Potential harm to the clinician is therefore reduced.

Reference is first made to FIG. 1, which depicts an infusion set generally designated at 10, including a safety needle assembly (“needle assembly”) 20 and one or more extension legs 24. The infusion set 10 is employed to gain access to a subcutaneously implanted access port or other device disposed below the skin of a patient in order to infuse medicaments or other fluids into the patient, and to withdraw fluids therefrom. A luer connector 26 is included on a proximal end of the extension leg 24 so as to enable the infusion set 10 to be placed into fluid communication with a fluid delivery device or system. A cap 28 can be disposed in the luer connector 26 to cover the opening thereof.

FIG. 1 shows that the needle assembly 20 includes a needle 30 extending from a handle 44 and in fluid communication with the tubing of the extension leg 24. A needle safety component 40 is also included in the needle assembly 20, including dual extensible wings that are hinged so as to be selectively extended to substantially cover the length of the needle 30 and isolate a distal end 30A thereof after use of the needle assembly 20 in order to prevent an unintended needle stick of the clinician by the needle tip. Examples of such a hinged safety assembly can be found in U.S. Pat. No. 5,951,522, which is incorporated herein by reference in its entirety.

As best seen in FIG. 2, the needle assembly 20 further includes a fluid isolation component 50 for isolating any fluid or vapor that may unintentionally escape from the needle 30 during use of the needle assembly. Specifically, the fluid isolation component 50 in the present embodiment includes absorbent pads 52 disposed on an inner surface 42A of each wing 42 of the needle safety component 40. The pads 52 are disposed such that when the wings 42 of the needle safety component 40 are deployed to cover the distal tip 30A of the needle 30 (FIG. 2), the pads sandwich the body and distal tip of the needle therebetween. Any fluid present on an external surface of the needle or any fluid/vapor leaking from the distal end thereof is captured and absorbed by the pads 52, thus preventing escape of the fluid, which as mentioned above may contain hazardous substances. This in turn protects the clinician from fluid exposure.

FIGS. 3A-3C show the manner in which the wings 42 of the needle safety component 40 extend to cover the needle 30 and its distal tip 30A, and additionally the manner in which the pads 52 sandwich and partially encapsulate the needle 30, including its external surfaces and its distal tip 30A, to prevent fluid/vapor escape. In one embodiment, the pads 52 can include an absorbent foam and/or rubber material, though many other suitable materials can be employed, including activated charcoal, etc.

FIGS. 4 and 5 show the infusion set 10 including a needle assembly 120 according to another embodiment, wherein the needle assembly includes a handle portion 122 with handles 124 extending therefrom. A needle 130 extends from the handle portion 122 and initially through a safety assembly 134 that is slidably disposed with respect to the needle 130 so as to be axially slidable therewith. The safety assembly 134 includes a base 136 that houses a needle safety component 140 (FIGS. 8A, 8B) for shielding a distal tip 130A of the needle 130 when use of the needle assembly is complete.

The needle assembly 120 further includes a fluid isolation component 150 for isolating any fluid or vapor that may unintentionally escape from the needle 130 during use of the needle assembly. Specifically, the fluid isolation component 150 in the present embodiment includes a conically shaped, extensible shroud 152 disposed about the body of the needle 130 and extending between the handle portion 122 and the axially slidable safety assembly 134. Including plastic such as PET or other substantially impermeable, collapsible, and suitable durable material, the shroud 152 forms a hollow cone about the needle 130 and is corrugated with corrugations 154 in a bellows-like manner to enable it to fold up compactly when the safety assembly 134 is undeployed (FIG. 4) and to extend to cover and substantially encompass the needle 30 when the safety assembly 134 is deployed (FIG. 5), i.e., the safety assembly is axially slid down the needle 130 toward the distal tip 130A such that the needle safety component 140 shields the distal tip. FIGS. 6A-6C depict the manner of deployment of the safety assembly 134 and the extension of the corrugated shroud 152. In the extended state shown in FIGS. 5 and 6C, the shroud 152 assists in isolating fluids/vapors present on the needle 130 or emitted from the needle distal tip 130A from contact with the clinician.

Note that examples of safety needles that can utilize principles discussed here and in other embodiments herein can be found in the following United States patent and patent applications: U.S. Pat. No. 7,717,888; Publication No. 2003/0114797; Publication No. 2008/0262434; and Publication No. 2010/0152677. Each of the afore-mentioned patents/patent applications is incorporated herein by reference in its entirety.

The shroud 152 as the fluid isolation component 150 can include other configurations. One such configuration is shown in FIGS. 7A-7C, wherein the shroud includes a plurality of interlocked, telescoping segments that are extendible to cover and encompass the needle body when the safety assembly 134 is deployed (FIG. 7C). When the safety assembly 134 is undeployed, the telescoping segments 156 are stacked together, as shown in FIG. 7A. Again, these and other configurations for encompassing the needle body illustrate manners by which a fluid isolation component can isolate the needle body and tip in order to prevent fluid exposure to clinician.

FIGS. 8A and 8B depict details of the needle safety component 140 of the needle assembly 120 of FIGS. 4-7C. Particularly, FIGS. 8A and 8B depict bottom views of the needle assembly 120. The needle safety component 140 is shown, including a coiled wire torsion spring 160 included within the base 136 of the safety assembly 134. The spring includes at one end thereof an obstruction component, i.e., a looped portion 162 that is biased to lie against the needle 130 when the needle extends through a hole 136A defined in the base 136 of the safety assembly 134, as shown in FIG. 8A. As shown in FIG. 8B, once the distal tip of the needle 130 is withdrawn into the base 136 in connection with extension of the safety assembly 134 (e.g., FIGS. 5, 6C, 7C), the spring 160 expands such that the looped portion 162 slides over the needle hole 136A to prevent re-emergence of the needle distal tip.

In addition, a fluid isolation component 170 is included with the spring 160 for isolating any fluid or vapor that may unintentionally escape from the needle 130 during use of the needle assembly. Specifically, the fluid isolation component 170 includes a shield 172, shown in FIGS. 8A and 8B, which is attached proximate the looped portion 162 of the spring 160. Thus, when the looped portion 162 slides over to prevent re-emergence of the distal tip 130A of the needle 130 through the hole 136A (FIG. 8B), the shield fully covers and occludes the hole so as to prevent any fluid/vapor leaking from the distal tip of the needle from exiting through the hole and potentially contaminating the environment or clinician. The shield 172 thus serves to occlude the hole 136A and isolate any fluids/vapors from the clinician. Note that the particular size, shape, and configuration of the shield can vary from what is shown and described herein, as can the particular configuration of the needle assembly. In one embodiment, it is appreciated that the shield can include an absorbent material so as to absorb any leaked fluid.

FIGS. 9A and 9B depict details of the needle assembly 120 according to another embodiment, including a fluid isolation component 180 for isolating any fluid or vapor that may unintentionally escape from the needle 130 during use of the needle assembly. As shown, the fluid isolation component 180 in the present embodiment includes a cylindrical absorption plug 182 included with the axially slidable safety assembly 134 of the needle assembly 120 and including a central cavity so as to be positioned about a portion of the body of the needle 130 (FIG. 9A). The central cavity of the plug 182 is sized such that the plug is able to wipe the outer surface of the body of the needle 130 as the safety assembly 134 is axially slid down the needle toward the distal tip 130A thereof, thus removing fluid from the outer needle surface and capturing it in the plug itself In addition, once the safety assembly 134 has fully shielded the needle distal tip 130A (FIG. 9B), the plug 182 is positioned about the distal opening of the lumen of the needle 130 so as to catch and absorb any fluids/vapors emanating therefrom.

It is appreciated that the absorption plug can include a variety of size, type, and material configurations, and can be employed on a variety of needle-based devices where residual fluid/vapor capture is desired. In one embodiment, for instance, the absorption member includes activated charcoal. In other embodiments, other materials and membranes can be employed, including silica gel, clays, activated alumina, zeolites, 0.2 micron or other filtration material, etc. The description included herein is therefore not intended to limit the present disclosure in any way.

FIG. 10 shows details of a fluid isolation component 200 according to another embodiment, including an absorption disk 202 included with the safety assembly 134. The absorption disk 202 is disposed above the needle safety component 140 in the safety assembly base 136 and is slit to enable the needle 130 to pass therethrough. Extension of the safety assembly 134 down the length of the needle 130 enables the absorption disk 202 to wipe the outer needle surface so as to remove any fluid present thereon. In addition, once the safety assembly 134 is fully extended to shield the needle 130 (FIG. 10), the absorption disk 202 is positioned so as to absorb any fluid/vapor leaking from the distal lumen opening at the needle distal tip 130A. As with the previous embodiment, the absorption disk 202 in one embodiment includes activated charcoal or other suitable, absorbent material as outlined above in connection with the absorption plug 182 shown in FIGS. 9A and 9B. The position, shape, thickness or other configuration of the absorption disk can vary from what is shown and described herein.

FIGS. 11-12B depict various details of a needle assembly 220 that can include a fluid isolation component, according to one embodiment. As shown, the needle assembly 220 includes a handle portion 222 from which extends a needle 230. The needle 230 initially extends through a safety assembly 234 that is slidably disposed with respect to the needle so as to be axially slidable therewith. The safety assembly 234 includes a base 236 that houses a needle safety component 240 (FIGS. 12A, 12B) for shielding a distal tip 230A of the needle 230 when use of the needle assembly is complete.

In greater detail, FIGS. 12A and 12B show that the needle safety component 234 includes two spring-based shutters 242 that each define a hole 244 through which the needle 230 passes when the needle extends through the safety assembly 234 and out a hole 236A defined in the base 236, such as in the configuration shown in FIG. 11. The shutters 242 each further include a spring arm 246. As seen in FIG. 12A, when the safety assembly 234 is undeployed (FIG. 11), the holes 244 of the shutters 242 are aligned so that the needle 230 passes therethrough. This constrains the shutters 242 and spring arms 246 into the configuration shown in FIG. 12A.

When the safety assembly 234 is actuated, however, it is slid down the length of the needle 230 so as to cause the needle distal tip 230A to recede from the hole 236A and the shutter holes 244 so as to be shielded within the safety assembly base 236. As shown in FIG. 12B, this causes the shutters 242 to no longer be constrained by the needle 230 and enables the shutter spring arms 246 to slide the shutters laterally within the base 236 so as to cover and occlude the hole 236A defined in the base, thus preventing reemergence of the needle distal tip 230A. Note that further information regarding this and other related needle safety assemblies can be found in U.S. Pat. No. 6,585,704 to Luther et al., entitled “Method of Retaining a Tip Protector on a Needle with a Curved Tip.”

In accordance with one embodiment the needle assembly 220 includes a fluid isolation component 250 for isolating any fluid or vapor that may unintentionally escape from the needle 130 during use of the needle assembly. Specifically, the fluid isolation component 250 in the present embodiment includes an absorption pad 252 disposed on a backside of one or both of the shutters 242 of the safety assembly 234. As shown in FIGS. 13 and 14, the pad 252 is disposed on the shutter 242 so that the distal tip 230A of the needle 230 rests against it after the distal tip has been withdrawn and shielded by the base 236 of the safety assembly 234. Should any fluid leak from the distal opening of the lumen of the needle 230, it can be readily captured by the pad 252, thus preventing its escape outside of the safety assembly 234. The pad can include one or more of suitable materials including those listed above in connection with the embodiment of FIGS. 9A and 9B, silicone, rubber, etc. As shown, the pad can also be recessed within the shutter 242 so as to provide a basin for capture of the fluid, in one embodiment. Note that the pad and shutters can vary in size, number, shape, design, etc.

FIG. 15 shows the needle assembly 220 including a fluid isolation component 260 according to one embodiment, wherein the fluid isolation component includes an O-ring 262 that is disposed within the safety assembly 234 about a portion of the needle 230. So positioned, the O-ring 262 wipes the length of the needle 230 when the safety assembly 234 is axially slid down the needle in order to shield the needle distal tip 230A. The O-ring 262 is sized such that its wiping action cleans the outer needle surface of any fluids that might otherwise be exposed to the clinician and prevents their escape from the safety assembly base 236. In one embodiment, the O-ring can be configured to be absorbent so as to soak up any fluid it comes into contact with during wiping of the needle. Note that the O-ring can be placed in other locations with respect to the needle safety assembly and that the needle housing and safety assembly can vary in configuration from what is shown.

FIGS. 16A and 16B depict various details of a needle assembly 320 including a fluid isolation component, according to one embodiment. The needle assembly 320 includes a handle portion 322 from which extends a needle 330. The needle 330 initially extends through a hole 344 defined in a safety assembly 334 that is pivotally movable with respect to the handle portion 322 and the needle 330 via a hinge point 338. The safety assembly 334 houses a needle safety component 340 including a laterally slidable shutter 342, disposed in a shutter cavity 346, for shielding a distal tip 330A of the needle 230 when use of the needle assembly is complete. A foam pad 354 is disposed on the bottom of the safety assembly 334.

As shown in FIG. 16B, the needle 330 is biased while residing in the hole 344 of the safety assembly 334 such that when the distal tip 330A is withdrawn from the hole, the needle 330 urges the shutter 342 to laterally slide within the shutter cavity 346, thus covering the hole and preventing re-emergence of the needle distal tip. In another embodiment, the shutter itself can be biased to urge the needle distal tip laterally.

The needle assembly 320 further includes a fluid isolation component, here configured as an extensible shroud 352 that extends about the needle 330 between the handle portion 322 and the safety assembly 334 to isolate the body of the needle and any vapors present therewith. Thus, the shroud 352 provides isolation of fluids present on the needle 330. In addition, the shutter 342 provides some fluid isolation as well.

FIGS. 17-18B disclose a luer connector 426 including a fluid isolation component, according to one embodiment. As shown, the connector 426 is a female-type luer connector, though the principles described here can be extended to other connective or fluid-carrying components of an infusion set or other suitable fluid delivery medical device. Connected to the extension leg tubing 24, the connector 426 includes a body that defines a cavity 428 suitable for receiving a male-type connector 456 (FIGS. 18A, 18B) therein. The connector 426 can include threads to enable the male connector 456 to threadably connect therewith. The cavity 428 defines a portion of a fluid pathway through the connector body.

A fluid isolation component 450 is included in the connector 426. In particular, the fluid isolation component 450 in the present embodiment includes a slit valve 452 that is disposed in the fluid pathway defined by the connector 426. Other suitable types of valves may also be employed.

As seen in FIGS. 18A and 18B, when the male connector 456 is received but not fully seated within the cavity 428 of the female connector 426, the valve 452 remains closed, thus isolating any fluid contained in the extension leg tubing 24 attached thereto. When the male connector 456 is fully inserted into the female connector 426, the distal end of the male connector engages and opens the valve 452, thus allowing fluid flow therethrough. This configuration of the connector 426 thus serves as one example a connector-based fluid isolation component; other configurations of this principle are contemplated.

FIGS. 19A and 19B depict another example of a fluid isolation component for preventing unintended contact with fluid or vapors resulting from use of an infusion set. In particular, an infusion set 10 is shown, including a needle assembly 220, extension leg tubing 24, and luer connector 26. Also shown is a fluid isolation component 470, which in the present embodiment includes a bag 472 of plastic or other substantially fluid-impermeable material. The bag includes a sealable open end 474 and a closed end 476. The bag 472 is attached to the tubing 24 of the infusion set 10 or other suitable component thereof via and adhesive strip 478 or other suitable connective apparatus.

The bag 472 is initially inside-out before use of the infusion set 10. Once use of the infusion set 10 has ended, the user reaches a hand through the open end 474 of the bag 472 and pulls the infusion set into the bag, turning the bag right side-out in the process. Once the infusion set 10 is fully within the bag 472, the open end 474 of the bag 472 is sealed, as seen in FIG. 19B, thus isolating the user from any fluids or vapors included on the needle assembly 220 or any other portion of the infusion set 10. Note that the bag can be configured in one or more sizes and shapes, can include one-time, resealable, or other suitable type of sealing mechanism, and can be included with the infusion set in a variety of ways, both attached and detached thereto. The bag in the present embodiment is transparent, though in other embodiments it need not be.

FIG. 20 depicts details of another possible fluid isolation component for use with the needle assembly 220 (shown in FIGS. 11-12B), or another suitable needle assembly. In particular, a fluid isolation component 480 is disclosed, including an amount of suitable viscous oil 482, such as silicone oil, interposed as a film between the shutters 242. When the needle 230 is retracted from the hole 236A in the needle assembly base 236, which retraction causes the shutters 242 to slide over and cover the hole, the oil 482 produces a fluid impermeable barrier layer between the shutters, thus preventing any fluid/vapor escaping the needle from escaping past the shutters. In other embodiments, other barriers can be employed between the shutters, including a gasket, 0-ring, other compliant/elastomeric member, etc.

Embodiments of the invention may be embodied in other specific forms without departing from the spirit of the present disclosure. The described embodiments are to be considered in all respects only as illustrative, not restrictive. The scope of the embodiments is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. 

What is claimed is:
 1. A needle assembly, comprising: a handle portion including a needle defining a lumen for passage of a fluid therethrough; a safety assembly selectively and axially slidable along the needle to shield a distal tip of the needle and prevent user contact therewith, the safety assembly including: a base including a needle hole; and a spring-based obstruction component biased to obstruct the needle hole after retraction of the needle distal tip into the base; and a fluid isolation component designed to isolate fluid escape from the needle.
 2. The needle assembly according to claim 1, wherein the fluid isolation component includes a shield attached to the obstruction component to prevent fluid escape from the safety assembly via the needle hole.
 3. The needle assembly according to claim 2, wherein the shield includes an absorbent component for absorbing fluid leaked from the needle.
 4. The needle assembly according to claim 1, wherein the fluid isolation component includes an absorption disk positioned to prevent fluid leakage from the needle through the needle hole in the safety assembly.
 5. The needle assembly according to claim 4, wherein the absorption disk includes activated charcoal.
 6. The needle assembly according to claim 1, wherein the spring-based obstruction component includes at least one shutter having a distal end designed to obstruct the hole, a proximal end coupled to the base, and a spring arm connecting the proximal end of the distal end.
 7. The needle assembly according to claim 6, wherein the fluid isolation component includes an absorbent pad disposed on the at least one shutter, the distal tip of the needle resting against the absorbent pad after retraction of the needle distal tip into the base, the absorbent pad isolating fluid leaked from the needle so as to prevent fluid escape from the safety assembly.
 8. The needle assembly according to claim 6, wherein the at least one shutter comprises a first shutter defining a first shutter hole, and a second shutter defining a second shutter hole, the needle extending through the first shutter hole, the second shutter hole, and the needle hole prior to retraction of the needle distal tip into the base.
 9. The needle assembly according to claim 8, wherein the fluid isolation component includes an oil film interposed between the first shutter and the second shutter to prevent escape of fluid from between the shutters.
 10. The needle assembly according to claim 9, wherein the fluid isolation component further includes an absorbent pad disposed on each of the first and second shutters.
 11. The needle assembly according to claim 1, wherein the fluid isolation component includes an O-ring disposed in the base to wipe an outer surface of the needle as the safety assembly is axially slid along the needle.
 12. The needle assembly according to claim 11, wherein the O-ring includes an absorbent material.
 13. The needle assembly according to claim 1, further comprising an extensible hollow shroud extending between the handle portion and the safety assembly so as to enclose a substantial portion of the needle after retraction of the needle distal tip into the base.
 14. The needle assembly according to claim 13, wherein the extensible hollow shroud is conically shaped and defines a plurality of interengaging elements.
 15. The needle assembly according to claim 14, wherein the interengaging elements include a plurality of predetermined, repeating surface features.
 16. The needle assembly according to claim 15, wherein the shroud includes plastic and wherein the repeating surface features include a plurality of corrugations defined by the surface of the shroud.
 17. The needle assembly according to claim 14, wherein the interengaging elements include a plurality of telescoping segments that are interlocked in series with one another.
 18. The needle assembly according to claim 14, wherein at least the shroud interconnects the handle portion and the safety assembly when the distal tip of the needle is shielded by the safety assembly.
 19. The needle assembly according to claim 1, wherein the handle portion is pivotally attached to the safety assembly at a pivot point.
 20. The needle assembly according to claim 19, further comprising an extensible hollow shroud extending between the handle portion and the safety assembly so as to enclose a substantial portion of the needle after retraction of the needle distal tip into the base. 